Up to now, fossil fuels, such as gasoline or light oil, has been used extensively not only as a source of energy for cars but also as a source of energy for power generation. Through the exploitation of this fossil fuel, the mankind could benefit from drastic improvement in life level and from remarkable industrial development. On the other hand, the earth is imperiled by the severe danger of environmental destruction, while depletion of the resources of the fossil fuel is feared to occur such that skepticism is entertained as to the prospect of its stable supply in the long term.
Hydrogen is contained in water and hence exists abundantly on earth. Moreover, it has a large chemical energy contained per unit mass, while it does not emit harmful gases or global warming gases when used as an energy source. For this reason, hydrogen is attracting general attention as a clean and plentiful energy source which should take the place of the fossil fuel.
Recently, researches and developments in electrical energy generating apparatus, capable of taking out the electrical energy from the hydrogen energy are going on briskly, such that there is a promising outlook towards application to large-scale power generation or on-site autogenous power generation and as a power source for cars.
An electrical energy generating apparatus for taking out the electrical energy from the hydrogen energy, that is a fuel cell, includes a hydrogen electrode, supplied with hydrogen, and an oxygen electrode, supplied with oxygen. Hydrogen supplied to a hydrogen electrode is dissociated by a catalytic action into protons and electrons. The electrons are collected by a current collector of the hydrogen electrode, while the protons are transported to the oxygen electrode. The electrons, collected by the hydrogen electrode, are transported through a load to the oxygen electrode. On the other hand, oxygen supplied to the oxygen electrode is bonded by a catalytic action to the protons and electrons, transported from the hydrogen electrode through a proton conducting film, to yield water. In this manner, an electromotive force is generated across the hydrogen electrode and the oxygen electrode to cause the current to flow through the load.
If hydrogen supplied to the hydrogen electrode directly reaches the oxygen electrode to react with oxygen or conversely the oxygen gas supplied to the oxygen electrode directly reaches the hydrogen electrode to react with hydrogen, the power generation efficiency is lowered because the power generated by this reaction is not passed through the load. That is, for raising the power generation efficiency, it is necessary to provide a proton conducting film whereby transmission of the hydrogen and oxygen gases therethrough is suppressed while efficient proton conduction therethrough is allowed. As such, a proton conduction film, a perfluorosulfonic acid resin, has so far been used.
The perfluorosulfonic acid resin is not optimum in its ability to suppress transmission of hydrogen and oxygen gases therethrough, such that, if this perfluorosulfonic acid resin is used as a proton conductor film, it has been difficult to raise the power generating efficiency sufficiently.